A study titled "Insight into synergistic antioxidation mechanisms of butyl hydroxyanisole with common synthetic antioxidants”was published in Grain & Oil Science and Technology in September 2022 revealing the synergistic antioxidant effect and mechanism of BHA with common synthetic antioxidants.^[1]

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Butylated hydroxyanisole (BHA) is a common synthetic antioxidant commonly applied to oils and oily foods to prevent the oxidation of oils,especially those with high unsaturated fatty acids. Chen et al.^[2] reported that during 3 weeks of storage at 60° C，BHA significantly improved the oxidation stability of sunflower oil (200 mg/kg BHA: peroxide value-102 mmol/kg，acid value-0. 34 mgK0H/g，P-aniside value-14. 7; compared to the control group: peroxide value-136 mmol/kg，acid value-0.71 mgK0H/g，P-aniside value-24. 0). Previous studies have shown that BHA has relatively weak antioxidant properties due to the stereotactic blocking caused by only one phenol hydroxyl group and tert-butyl group. Therefore, thus BHA is usually used in combination with other synthetic antioxidants and shows excellent synergistic antioxidant effects.

In this study, the synergistic antioxidant effects of BHA,BHT and TBHQ were investigated by AAPH oxidation system. The content of BHA, BHT, TBHQ and conversion products were determined by HPLC. The transformation products were identified by LC-MS and GC-MS.

The results showed that compared with AAPH-oxidizing BHA and AAPH-oxidizing BHT alone，the BHT loss rate of AAPH-oxidizing BHA+BHT system was significantly increased (P<0. 05)，but the BHA loss rate was significantly decreased (P<0. 05). It is concluded that when BHA is mixed with a synergist with the same antioxidant activity (e.g. BHT)，BHA and the synergist BHT competitively perform antioxidant activity. Once a collision occurs，BHA can be regenerated by a synergist.

When BHA is mixed with a synergist with high antioxidant activity (such as TBHQ),the percentage of remaining BHA in the AAPH-oxidizing BHA+TBHQ system

remains unchanged,while the percentage of remaining BHA in the AAPH-oxidizing BHA system is significantly reduced. The percentage of remaining TBHQ in the BHA+TBHQ system oxidized by AAPH is similar to that in the TBHQ system oxidized by AAPH. This suggests that the synergistic antioxidant effect of BHA and

TBHQ is largely related to the protective mechanism of TBHQ.

The Rancimat method was used to analyze the antioxidant properties of BHA,BHT and TBHQ in lard. The results showed that compared with the control, the lard IP which added BHA,TBHQ and BHT increased greatly. The IP of lard with higher antioxidant content was much longer than that of lard with lower antioxidant content. The synergistic effect of BHA+BHT and BHA + TBHQ mixtures was 18. 03% and 4. 54%, respectively，which further confirmed the synergistic effect of BHA with BHT and TBHQ.

Table 1: Synergistic Effects of BHA, BHT and TBHQ in lard

Note: Different lower case letters indicate significant differences in the values of the same column (P<0.05).

This study reported the law of loss of BHA and synergist in the process of synergistic antioxidant,and revealed the synergistic antioxidant mechanism of BHA and synergist.This will facilitate the innovative use of BHT in the future and has guiding significance for the use of BHA and several other synthetic antioxidants.

References:

[1]Jun Li, Jiali Chen, Yanlan Bi, Huifang Yang,Insight into synergistic antioxidation mechanisms of butyl hydroxyanisole with common synthetic antioxidants,Grain & Oil Science and Technology,Volume 5, Issue 3,2022,Pages 114-130.

[2]X.Chen,Y.Zhang,Y.Zu,et al.Antioxidant effects of rosemary extracts on sunflower oil compared with synthetic antioxidants.Int.J.Food Sci. Technol.,49(2014), pp.385-391.